Hi all. Here is the deal, my truck has 85,000+- miles on it has always had a rear end noise but it has been getting worse over the last few weeks. Put a trailer on the back not to long ago and it made it really bad. I serviced the fluid with synthetic and the noise got worse over the next few day. Put the truck in the air you can hear a noise from the pinion. So I changed the U-joint thinking maybe it was going bad and thats easier then the pinion. noise is worse now. So I pulled everything apart expecting to find a bad bearing and EVERY THING LOOKS GOOD. So... I dont want to spend anymore money then necessary to fix this but not sure what I should replace. any Ideas was thinking that the synthetic fluid was to thin and transmitted the noise better. rear went from factory fill to Valvoline at about 40k then just recently within the last few hundred miles mobile one... Tired of all these problem with this truck lately was good till I got it paid off

HELP.
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Just a guess,but it could be the rear end ring and pinion gear contact parrern. It could have been installed incorrectly, not ground perfectly to match up with each other or could have broken teeth, leaving metal shavings behind.

 

no broken teeth on he gears and patter looks fine it really wasnt a gear noise but a bearing noise.

 

My rear diff has been a little noisy since new. It really hasn't changed much and I now have 112K miles on her. Drive and smile.

 

I had the same noise in mine. Found that the inner race of the large bearing was all chewed up. Looked like it wasn't heat treated correctly. After I removed the bearing I rotated the outer cage while holding the inner race and felt it grinding.

 

My rear diff has always been noisy, but only for the first few miles. After is warms up, no whining/howling. I have just under 100k. I hear it less now that I have a loud exhaust.

 

It could be a bad pinion bearing. Do you hear it more during acceleration or deceleration? Is the noise consistent with speed or does it wind up louder with shifts in the transmission?

 

The faster you go the louder it gets

 

Does it seem like a high pitched noise or lower pitched noise? When you said that you pulled everything apart did you pull the carrier out of the housing or just pull the cover? Did the differential oil have a silvery or metallic look to it? Do you have a pictures of the differential, ring gear or bearings? It will be easier to diagnose with as much information as we can gather about the symptoms.

 

Does the plug magnet have a substantial amount of grey or silver goo on it?

 

it had some...